Play It Safe on Social Networks

En español | In October, Facebook announced it had 1 billion active members — people who access their pages at least once a month. Despite warnings that it and other social network sites are the new frontier for fraud, many people continue to post the kind of information that scammers can piece together for identity theft.

For instance, two of three profiles include birthdays and nearly as many provide a high school name, giving clues to where the users grew up. With a birthdate and hometown, scammers can guess most, if not all, of the nine digits of your Social Security number, researchers say.

Roughly half of profiles include email addresses (spammers love them) and about one in five has a phone number. Too often there's information about family members and even pets and mother's maiden name — popular security questions used by websites to authenticate a user's identity.

What's more, roughly one in four Facebook users has a "public" profile that allows anyone to see such information, estimates the 2012 Identity Fraud Industry Report by Javelin Strategy & Research.

Maybe that explains why Javelin estimates that Facebook users with public profiles report being victims of identity theft nearly twice as often as others. The rate is even higher among those who accept "friend" requests from strangers.

And it's not just Facebook. Users of LinkedIn, the popular employment-oriented website, often include current and past jobs, if not more data that's useful to identity thieves. LinkedIn's users are more than twice as likely to report being victimized, according to the Javelin survey, which covered more than 5,000 respondents.

"Almost everything you say and do on social networks is public by default," says Sarah Downey, privacy analyst for Abine, which offers free software that blocks companies from tracking your online wanderings. "And a lot of scams occur because there's too much personal information out there."

• Set privacy controls. Some 13 million Facebook users in the United States never do, says Consumer Reports — and with dozens of possible settings, it can be confusing. "So start by turning off tag suggestions, turn on tag and profile review, disable access to apps you don't use or trust, and only share with friends," suggests Downey. At other social networking websites, try to make your profile as private as possible.

• Be careful posting photos. No matter how strong your privacy settings, your name and profile photo will be out there for the world to see. At the least, turn off Tag Suggest to avoid Facebook automatically recognizing your face in photos.

• Block "snooping" apps. Unless you intercede, notes Consumer Reports, friends can use them to share personal information about you.